A magnetic bone conduction hearing aid is held in position on a patient's head by means of magnetic attraction that occurs between magnetic members included in the hearing aid and magnetic members included in a magnetic implant that has been implanted beneath the patient's skin, and that has been affixed to the patient's skull. If a patient's skin or tissue at such a single location is particularly thin or becomes irritated or inflamed while the magnetic hearing aid is being worn, or if the patent is uncomfortable, or experiences discomfort or pain when wearing the hearing aid, then the only effective remedy for the pain or discomfort may be to remove the magnetic hearing aid from the patient's head. In addition, a magnetic bone conduction hearing aid must possess sufficient magnetic coupling capability to remain secured to a patient's skull during everyday use.
Many patients wearing magnetically-coupled hearing aids regularly experience episodes of accelerative forces caused, for example, by patients hopping, jumping or being jarred. Magnetic bone conduction hearing aids must therefore possess sufficient magnetic coupling forces to withstand such forces and yet remain attached to the patient's skull. On the other hand, magnetic coupling forces provided by magnetic bone conduction hearing aids cannot be excessive, for otherwise tissue necrosis or ischemia can develop in the tissue underlying magnetic spacer.
Skull bone geometries, tissue thicknesses, patient susceptibility to pain or discomfort, and magnetic implant positions also vary from patient to patient.
The above factors complicate comfortable, effective and suitable or sufficiently strong magnetic coupling of magnetic bone conduction hearing aids to patient's skulls.
What is needed is a magnetic bone conduction hearing aid and corresponding magnetic implant that permit a hearing aid to be positioned comfortably on a chronic basis on a variety of different patients' skulls.